1. Field of the Invention
The present invention relates to high data capacity bar codes for non-linear strain measurement. More specifically, the invention relates to a high-data capacity, segmented circular bar code geometry that utilizes locator rings, orientation cells, and data cells in multiple concentric rings, which can be used for non-linear strain analysis and measurement.
2. Related Art
Bar codes are “machine readable” markings that are used to encode and store information in a normal geometric pattern, or compressed symbol. Possibly the most familiar bar code is the one-dimensional (1 D) pattern of alternating black and white bars found on labels and price tags of nearly every consumer item (commonly referred to as a universal price code or UPC).
The need to store greater amounts of information in a compact symbol gave rise to two-dimensional (or 2 D) bar codes. Early 2 D bar codes were simply multiple rows of 1 D bar codes. Matrix-type codes later evolved with black and white dots or squares arranged in a regular rectangular pattern. Today there are a variety of 2 D bar code patterns. Examples are 3-DI, Aztex, Codablock, Code 1, Code 16K, Code 49, CP Code, DataGlyph, DataMatrix, Datastrip Code, Dot Code A, Hue Code, Intacta Code, MaxiCode, MiniCode, PDF 417, QR Code, SmartCode, Snowflake Code, SuperCode, and UltraCode. Of the 2 D bar codes listed above, only the 3-DI code (described in U.S. Pat. No. 5,554,841 assigned to Lynn Ltd.) is based on a circular geometry. DMI is aware of an additional circular bar code (U.S. Pat. No. 5,798,514) that utilizes lengths of opposing radial “teeth” to encode data.
While a variety of bar code configurations exist today, the inventor and his assignee (Direct Measurement Inc.) have identified a need for a high-data capacity circular bar code with certain geometric properties not presently available in existing bar code configurations.
It is to the solution of these and other problems that the present invention is directed.